The present invention relates to a novel glucose dehydrogenase usable for glucose determination in clinical laboratory tests and to a method for producing same.
Promoted by the recent spread of clinical examinations, glucose dehydrogenases usable for glucose determination have been in great demand. In particular, development of a glucose dehydrogenase which is excellent in thermal stability is desired in the field of dry chemistry among the fields of clinical examinations.
Presently-available glucose dehydrogenases usable for clinical examinations are glucose dehydrogenase (EC1.1.1.47) derived from the genus Bacillus and glucose dehydrogenase (EC1.1.1.119) derived from the genus Cryptococcus. The former is an enzyme which catalyzes the reaction of .beta.-D-glucose+NAD(P).sup.+ .fwdarw.D-.delta.-gluconolactone+NAD(P)H+H.sup.+, and the latter is an enzyme which catalyzes the reaction of D-glucose+NADP.sup.+ .fwdarw.D-.delta.-gluconolactone+NADPH+H.sup.+. For use in clinical examinations, the glucose dehydrogenase (EC1.1.1.47) capable of using both NADP and NAD as a coenzyme is more preferable than the glucose dehydrogenase (EC1.1.1.119) capable of using NADP solely as a coenzyme.
Yet, every glucose dehydrogenase (EC1.1.1.47) presently available on the market is unstable to heat, and development of a glucose dehydrogenase superior in thermal stability as an enzyme for clinical examinations, particularly for dry chemistry, has been desired.
While the origin of the conventional glucose dehydrogenase (EC1.1.1.47) has been known to be various bacteria such as the genus Bacillus and animal livers (see Koso Handobukku, 9th ed., p. 19, Asakurashoten), an NAD(P)-dependent glucose dehydrogenase derived from the genus Pseudomonas has not been known. In addition, the known glucose dehydrogenase produced by the bacteria belonging to the genus Pseudomonas is an NAD(P) non-dependent glucose dehydrogenase (EC1.1.99.a) [Methods in Enzymology, vol. 9, 92-98 (1966), Agric. Biol. Chem., 44 (7), 1505-1512 (1980)] which is difficult to use in clinical fields.